Document conveying device

ABSTRACT

A document conveying device includes a sheet feeding tray, a discharge tray, a conveying mechanism and a document pressing member. On the sheet feeding tray, a document is placed. The discharge tray is provided below the sheet feeding tray. The conveying mechanism conveys the document from the sheet feeding tray to the discharge tray via a reading position. The document pressing member is provided on a lower surface of the sheet feeding tray, is capable of protruding and contracting in directions close to and away from the discharge tray, and presses the document discharged on the discharge tray.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese patent application No. 2022-035397 filed on Mar. 8, 2022, which is incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a document conveying device which conveys a document to a reading position.

In recent years, a request for a large capacity document conveying device provided in a document reading device is increased, and a technology for achieving a large capacity has been discussed. For example, in a document feeding device in which documents placed on a sheet feeding tray are fed one by one from the upper document to a conveyance path by a feeding part and discharged sequentially in a stackable manner through a discharge port onto a discharge tray provided directly below the sheet feeding tray via an image reading position in the conveyance path, a lifting means for lifting and lowering the sheet feeding tray and a lifting and lowering control means for lifting and lowering the discharge tray in response to the feeding of the placed documents from the sheet feeding tray are provided, and the discharge port is configured to be lift and lowered by the same amount in response to the lifting and lowering of the sheet feeding tray.

However, in the above configuration, there is a problem that when a small amount of documents are placed on the sheet feeding tray, a distance between the discharge port and the discharge tray becomes large, and the documents are scattered on the discharge tray. Therefore, it is possible to improve the alignment of the documents by providing a document pressing member to press the upper surface of the discharged document.

In a case where the discharge tray is provided below the sheet feeding tray, the document pressing member needs to be provided on the lower surface of the sheet feeding tray via a rotational fulcrum in order to accommodate a change in the amount of the documents stacked on the discharge tray. When there are no documents on the discharge tray or there are few documents on the discharge tray, the document pressing member is in a drooping posture and comes into contact with the tip end portion of the discharged document to drop the document on the discharge tray so that the document is prevented from flying far. However, as the number of documents on the discharge tray increases, the inclination of the document pressing member increases. Then, the position where the tip end portion of the document comes in contact with the document pressing member becomes far from the discharge port, and the alignment of the discharged document is degraded.

In addition, when the capacity of the document conveying device is increased, the maximum distance between the sheet feeding tray and the discharge tray increases. However, if the document pressing member is made longer, the inclination of the document pressing member is increased when the sheet feeding tray is lowered or when a large amount of documents are stacked on the discharge tray, and the alignment of the discharged documents is degraded. In addition, if the document pressing member is made longer, the force to press the documents becomes excessive when a large amount of documents is stacked on the discharge tray. On the other hand, if the document pressing member is made shorter to decrease the inclination of the document pressing member, there is a risk that the document may not come into contact with the document pressing member when the sheet feeding tray is lifted and there are few documents on the discharge tray.

SUMMARY

In accordance with one aspect of the present disclosure, a document conveying device includes a sheet feeding tray, a discharge tray, a conveying mechanism and a document pressing member. On the sheet feeding tray, a document is placed. The discharge tray is provided below the sheet feeding tray. The conveying mechanism conveys the document from the sheet feeding tray to the discharge tray via a reading position. The document pressing member is provided on a lower surface of the sheet feeding tray, is capable of protruding and contracting in directions close to and away from the discharge tray, and presses the document discharged on the discharge tray.

The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view schematically showing an inner structure of an image forming apparatus according to one embodiment of the present disclosure.

FIG. 2 is a perspective view showing an appearance of a document conveying device according to the embodiment of the present disclosure.

FIG. 3 is a perspective view schematically showing a sheet feeding mechanism and a conveying mechanism according to the embodiment of the present disclosure.

FIG. 4 is a front view schematically showing the conveying mechanism and a sheet feeding tray lifting mechanism according to the embodiment of the present disclosure.

FIG. 5 is a rear view schematically showing the sheet feeding tray lifting mechanism and a driving part according to the embodiment of the present disclosure.

FIG. 6 is a front view schematically showing the conveying mechanism and the sheet feeding tray lifting mechanism according to the embodiment of the present disclosure.

FIG. 7 is a front view showing a discharge port lifting mechanism according to the embodiment of the present disclosure.

FIG. 8 is a front view showing the discharge port lifting mechanism according to the embodiment of the present disclosure, in which the driving part shown in FIG. 7 is omitted.

FIG. 9 is a sectional view showing a guide part according to the embodiment of the present disclosure.

FIG. 10 is a sectional view showing a state where the guide part shown in FIG. 8 is lifted, according to the embodiment of the present disclosure.

FIG. 11 is a perspective view showing a document pressing member according to the embodiment of the present disclosure.

FIG. 12 is a perspective view showing the document pressing member according to the embodiment of the present disclosure.

FIG. 13 is a front view showing the document conveying device provided with the document pressing member according to the embodiment of the present disclosure.

FIG. 14 is a front view explaining an operation of the document conveying device according to the embodiment of the present disclosure.

FIG. 15 is a front view explaining the operation of the document conveying device according to the embodiment of the present disclosure.

FIG. 16 is a front view explaining the operation of the document conveying device according to the embodiment of the present disclosure.

FIG. 17 is a front view explaining the operation of the document conveying device according to the embodiment of the present disclosure.

FIG. 18 is a front view explaining the operation of the document conveying device according to the embodiment of the present disclosure.

FIG. 19 is a front view explaining the operation of the document conveying device according to the embodiment of the present disclosure.

FIG. 20 is a front view explaining the operation of the document conveying device according to the embodiment of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, with reference to the drawings, a document conveying device 120 and an image forming apparatus 100 according to one embodiment of the present disclosure will be described.

First, an entire structure of the image forming apparatus 100 will be described. FIG. 1 is a front view schematically showing an inner structure of the image forming apparatus 100. Hereafter, the front side of the paper plane on which FIG. 1 is drawn is defined as the front side of the image forming apparatus 100, and the left-and-right direction is described with reference to the direction in which the image forming apparatus 100 is viewed from the front side. In each figure, U, Lo, L, R, Fr and Rr indicate upper, lower, left, right, front and rear, respectively.

The image forming apparatus 100 includes a printer 1, a scanner 110 and the document conveying device 120. The scanner 110 is provided above the printer 1, and the document conveying device 120 is provided above the scanner 110. The document conveying device 120 conveys the document G through a reading position of the scanner 110. The scanner 110 is a flatbed type image scanner, reads the document G and generates image data. The printer 1 forms an image on the sheet S based on the image data. While the present embodiment shows an example in which the printer 1 forms the image by an electrophotographic method, the printer 1 may be configured to form an image by an inkjet method.

The printer 1 includes a box-shaped main body housing 3. In the lower portion of the inside of the main body housing 3, a sheet feeding cassette 4 in which the sheet S is stored and a sheet feeding roller 5 which feeds the sheet S from the sheet feeding cassette 4 rightward are provided. Above the sheet feeding cassette 4, an image forming device 6 which forms a toner image in an electrophotographic method is provided, and on the right upper side of the image forming device 6, a fixing device 7 which fixes the toner image to the sheet S is provided. Above the fixing device 7, a discharge roller 8 which discharges the sheet S on which the toner image is fixed and a discharge tray 9 on which the discharged sheet S is stacked are provided.

Inside the main body housing 3, a conveyance path 10 is provided from the sheet feeding roller 5 through the image forming device 6 and the fixing device 7 to the discharge roller 8. The conveyance path 10 is formed mainly of plate-like members facing each other with a gap for passing the sheet S, and conveyance rollers 17 which hold and convey the sheet S are provided at multiple positions in the conveying direction Y. A registration roller 18 is provided on the upstream side of the image forming device 6 in the conveying direction Y. On the right side of the fixing device 7, an inversion conveyance path 10R branching from the conveyance path 10 on the downstream side of the fixing device 7 in the conveying direction Y and merging with the conveyance path 10 on the upstream side of the registration roller 18 in the conveying direction Y is provided.

A controller 2 is provided with an arithmetic part and a storage part (not shown). The arithmetic part is, for example, a CPU (Central Processing Unit). The storage part includes storage media, such as ROM (Read Only Memory), RAM (Random Access Memory) and EEPROM (Electrically Erasable Programmable Read Only Memory). The arithmetic part performs various processes by reading and executing the control program stored in the storage part. The controller 2 may be realized only by an integrated circuit without using software.

A display operation part (not shown) is provided on the front side of the scanner 110. The display operation part includes a display panel, a touch panel provided on the display surface of the display panel and a keypad adjacent to the display panel (not shown). The controller 2 makes the display panel display a screen showing the operation menu, status or the others of the printer 1 and the scanner 110, and controls each part of the printer 1 and the scanner 110 according to the operation detected by the touch panel and the keypad.

The basic image forming operation of the printer 1 is as follows. When a single-sided printing job is input to the printer 1 from the display operation part or an external computer, the sheet feeding roller 5 feeds the sheet S from the sheet feeding cassette 4 to the conveyance path 10, the registration roller 18 whose rotation is stopped corrects the skew of the sheet S, and the registration roller 18 feeds the sheet S to the image forming device 6 at a prescribed timing. The image forming device 6 forms a toner image on the sheet S by an electrophotographic method. Subsequently, the fixing device 7 melts the toner image while holding and conveying the sheet S to fix the toner image on the sheet S. The discharge roller 8 discharges the sheet S to the discharge tray 9. In the case of duplex printing, the sheet S on which the toner image is fixed on the first side is fed to the conveyance path 10 via the inversion conveyance path 10R, and then the toner image is transferred to the second side of the sheet S.

[Scanner] The scanner 110 includes a first carriage 81 with a light source and a reflection mirror, a second carriage 82 with two reflection mirrors, a lens 83 for focusing light, an imaging element 84 for converting the focused light into image data, and a contact glass 85 on which the document G is placed.

The basic document reading operation of the scanner 110 is as follows. When the user places the document G on the upper surface of the contact glass 85 and gives a reading instruction to the scanner 110, the first carriage 81 moves rightward at a speed V while the second carriage 82 moving rightward at a speed V/2. During this time, the light source irradiates the document G with light, and the reflected light reflected by the document G is reflected by the reflection mirror of the first carriage 81 and the reflection mirrors of the second carriage 82, guided to the lens 83, focused by the imaging element 84, and converted into an image signal. The image signal is output to the controller 2 of the printer 1 and converted into the image data.

[Document Conveying Device] Next, the document conveying device 120 will be described. FIG. 2 is a perspective view showing the appearance of the document conveying device 120. FIG. 3 is a perspective view showing a sheet feeding mechanism 31 and a conveying mechanism 32. FIG. 4 and FIG. 6 are front views schematically showing the conveying mechanism 32 and a sheet feeding tray lifting mechanism 33. FIG. 5 is a rear view schematically showing the sheet feeding tray lifting mechanism 33 and a driving part 68. FIG. 3 , FIG. 4 and FIG. 5 show a state where a sheet feeding tray 44 is positioned at the upper limit position, and FIG. 6 shows a state where the sheet feeding tray 44 is positioned at the lower limit position. FIG. 3 to FIG. 6 does not show a document pressing member 21.

The document conveying device 120 includes a sheet feeding tray 44 on which the document G is placed; a discharge tray 43 provided below the sheet feeding tray 43; the conveying mechanism 32 which conveys the document G from the sheet feeding tray 44 to the discharge tray 43 via a reading position (an opening 40A); and a document pressing member 21 provided on the lower surface of the sheet feeding tray 44, expanding and contracting in directions close to and away from the discharge tray 43 and pressing the document G discharged on the discharge tray 43.

The document conveying device 120 (see FIG. 2 ) has an approximately rectangular bottom portion 40 formed into a flat shape, and a first wall portion 41 and a second wall portion 42 facing each other in the front-and-rear direction (the width direction intersecting the conveying direction Z of the document G). The rear edge portion of the bottom portion 40 is hinged on the rear side of the contact glass 85 of the scanner 110. The bottom portion 40 also functions as a presser plate to press the document G on the contact glass 85. The first wall portion 41 is provided from the left end portion to the center portion of the front edge portion of the bottom portion 40. The second wall portion 42 is provided over the rear edge portion of the bottom portion 40. A cover portion 46 covers the upper and left sides of the space between the first wall portion 41 and the second wall portion 42. The left lower end portion of the cover portion 46 is hinged to the left end portion of the bottom portion 40.

[Sheet Feeding Try] The sheet feeding tray 44 (see FIG. 2 and FIG. 3 ) is provided on the right side of the center portion in the left-and-right direction of the document conveying device 120 and on the front side of the second wall portion 42. The sheet feeding tray 44 is a plate-like member inclined with its left side downward. On the upper surface of the sheet feeding tray 44, a pair of cursors 45 are provided to align the front and rear ends of the document G.

[Discharge Tray] The discharge tray 43 is provided below the sheet feeding tray 44. The discharge tray 43 is integral with the bottom portion 40. On the center portion in the left-and-right direction of the discharge tray 43, an inclined surface with its left wide downward is provided. On the left end portion of the discharge tray 43, a wall portion 47 with which the left end portion of the discharged document G comes into contact is provided.

[Sheet Feeding Mechanism] The sheet feeding mechanism 31 (see FIG. 3 ) is provided in the space between the first wall portion 41 and the second wall portion 42. The sheet feeding mechanism 31 has a box-shaped holder 53 with the lower surface opened. Inside the holder 53, a feeding roller 51, a driven roller 55, a driving roller 52 and an endless belt 56 are arranged with their axial directions along the front-and-rear direction. The driven roller 55 is disposed on the left side of the feeding roller 51. The driving roller 52 is disposed on the left side of the driven roller 55. The endless belt 56 is wound around the driving roller 52 and the driven roller 55. An auxiliary roller 57 with its axial direction along the front-and-rear direction is pressed against the lower surface of the lower part of the endless belt 56.

Both the front and rear end portions of the driving shaft 54 of the driving roller 52 are supported by the first wall portion 41 and the second wall portion 42, and are connected to a driving part (not shown) which includes a motor and a reduction gear. The holder 53 is supported by the driving shaft 54, and is swingable around the driving shaft 54. The driving force of the driving shaft 54 is transmitted to the feeding roller 51 by a transmission mechanism (not shown) such as a gear train or an endless belt.

A sensor 58 detects the sheet feeding tray 44 positioned at which the document G can be fed. The sensor 58 is a transmission or reflection type optical sensor, and is provided on the inner surface of the cover portion 46. A light shielding plate 59 projecting upward or sideways is provided on the upper portion of the holder 53.

[Sheet Feeding Tray Lifting Mechanism] The sheet feeding tray lifting mechanism 33 (see FIG. 4 and FIG. 5 ) is provided on the front surface of the first wall portion 41 and the rear surface of the second wall portion 42. A driving pulley 71 and a driven pulley 72 (see FIG. 5 ) are provided above and below the center of the rear surface of the second wall portion 42, respectively. A driven pulley 73 is provided at a height between the driving pulley 71 and the driven pulley 72 and on the left side of the driving pulley 71 and the driven pulley 72. A guide pulley 76 is provided on the left upper side of the driven pulley 72 and on the right side of the driven pulley 73. An endless belt 70 is wound around the driving pulley 71, the driven pulleys 72 and 73 and the guide pulley 76. A driving part 78 includes a motor 78M, a worm gear 78W, an idler gear 78 i and a driving gear 71G. The driving gear 71G is coupled to the shaft of the driving pulley 71.

Driven pulleys 91, 92 and 93 and a guide pulley 96 (see FIG. 4 ) are provided on the front surface of the first wall portion 41 at positions facing the driving pulley 71, the driven pulleys 72, 73 and the guide pulley 76, respectively. An endless belt 90 is wound around the driven pulleys 91, 92 and 93 and the guide pulley 96. The driven pulley 93 is provided to the common shaft with the driven pulley 73.

A sliding part 74 (see FIG. 5 ) is provided in the left end portion of the rear edge portion of the sheet feeding tray 44. The second wall portion 42 has a first slit 421 whose longitudinal direction is along the upper-and-lower direction. The first slit 421 is provided at a position corresponding to the left end portion of the rear edge portion of the sheet feeding tray 44. The sliding part 74 is connected to the endless belt 70 between the driving pulley 71 and the driven pulley 72 through the first slit 421.

A lifting guide part 75 is provided on the rear surface of the second wall portion 42. The lifting guide part 75 is a rail-like member whose longitudinal direction is along the upper-and-lower direction. The sliding part 74 can slide upward and downward along the lifting guide part 75.

A sliding part 94 (see FIG. 4 ) is provided in the left end portion of the front edge portion of the sheet feeding tray 44. The sliding part 94 is connected to the endless belt 90 between the driven pulley 91 and the driven pulley 92.

A lifting guide part 95 is provided on the front surface of the first wall portion 41. The lifting guide part 95 is a rail-like member whose longitudinal direction is along the upper-and-lower direction. The sliding part 94 can slide upward and downward along the lifting guide part 95.

The basic operation of the sheet feeding tray lifting mechanism 33 is as follows. The driving force generated by the motor 78M is transmitted to the driving gear 71G via the worm gear 78W and the idler gear 78 i. The endless belt 70 travels by the rotation of the driving pulley 71 together with the driving gear 71G, and the driven pulleys 72 and 73 are rotated accordingly. When the driven pulley 93 is rotated together with the driven pulley 73, the endless belt 90 travels in synchronization with the endless belt 70. Since the sheet feeding tray 44 is connected to the endless belts 70 and 90 via the sliding parts 74 and 94, the forward and reverse rotation of the motor 78M lifts and lowers the sheet feeding tray 44.

The controller 2 makes the sheet feeding tray lifting mechanism 33 lift the sheet feeding tray 44. When the upper surface of the document G placed on the sheet feeding tray 44 is pressed against the feeding roller 51, the holder 53 swings upward. When the holder 53 swings upward by a predetermined amount, the light shielding plate 59 blocks the light of the sensor 58. At this time, an appropriate load acts between the upper surface of the document G and the feeding roller 51, and the document G can be fed by the feeding roller 51. In other words, the controller 2 controls the sheet feeding tray lifting mechanism 33 so as to lift the sheet feeding tray 44 as the amount of documents G placed on the sheet feeding tray 44 decreases.

[Conveying Mechanism] The conveying mechanism 32 (see FIG. 3 ) includes a conveyance path 61 from the sheet feeding mechanism 31 to an opening 40A, a plurality of conveying rollers 62 arranged on the conveyance path 61 and a guide part 64 from the opening 40A to a discharge roller 69. The conveyance path 61 and the guide part 64 are formed mainly by plate-shaped members facing each other with a gap through which the document G can be passed. The opening 40A is a slit whose longitudinal direction is along the front-and-rear direction, provided at a region of the bottom portion 40 facing the first carriage 81 (see FIG. 1 ) positioned at the home position. The opening 40A is an example of the reading position where the scanner 110 reads the document G. At the reading position, an opening 61A corresponding to the opening 40A is provided in the plate-shaped member on the lower side of the conveyance path 61, and the lower surface of the document G being conveyed is exposed downward through the opening 40A and the opening 61A.

The conveying roller 62 includes a driving roller 62D and a driven roller 62N (see FIG. 3 ). A driven pulley 63N (see FIG. 4 ) is provided on the shaft of the driving roller 62D. A driving pulley 63D is connected to a driving part (not shown) including a motor and a reduction gear. An endless belt 60 is wound around the driving pulley 63D, a plurality of the driven pulleys 63N and a guide pulley 63G. When the driving pulley 63D is driven, the driven pulleys 63N rotate synchronously by the traveling of the endless belt 60, so that the conveying rollers 62 also rotate synchronously.

[Discharge Port Lifting Mechanism] FIG. 7 is a front view showing the discharge port lifting mechanism 34. FIG. 8 is a front view showing the discharge port lifting mechanism 34 in which the driving part 68 shown in FIG. 7 is excluded. FIG. 9 is a sectional view showing the guide part 64. FIG. 10 is a front view showing a state where the guide part 64 shown in FIG. 8 is lifted.

[Guide Part] The guide part 64 (see FIG. 7 to FIG. 10 ) is formed by integrating a lower guide member 65 and an upper guide member 66 which face each other in the upper-and-lower direction. The lower guide member 65 (see FIG. 9 ) includes an approximately rectangular plate-shaped portion 65P forming the lower portion of the conveyance path 61 and support portions 65S supporting both the front and rear end portions of the plate-shaped portion 65P. The upper guide member 66 includes an approximately rectangular plate-shaped portion 66P forming the upper portion of the conveyance path 61 and support portions 66S supporting both the front and rear end portions of the plate-shaped portion 66P. The left end portions of the front and rear support portions 66S of the upper guide member 66 are supported by the shaft (the first turning shaft 661) of the driving roller 62D of the conveying roller 62 adjacent to the right side of the opening 40A. The guide part 64 is turnable around the first turning shaft 661.

The discharge roller 69 is provided at the right end portion of the guide part 64. The discharge roller 69 includes a driving roller 69D and a driven roller 69N disposed above the driving roller 69D. The driving roller 69D is supported by the right end portion of the support portion 65S of the lower guide member 65, and the driven roller 69N is supported by the right end portion of the support portion 66S of the upper guide member 66. The contact area between the driving roller 69D and the driven roller 69N is located at the downstream end portion of the guide part 64 in the conveying direction Z, and serves as a discharge port 69A through which the document G is discharged from the guide part 64.

A cylindrical protrusion 65B is provided on the front and rear support portions 65S of the lower guide member 65 (see FIG. 9 ). The protrusion 65B is formed, for example, by inserting a calking pin into a through-hole formed in the support portion 65S. The protrusion 65B is located away from the first turning shaft 661. In this embodiment, the protrusion 65B is provided on the right side of the center of the lower guide member 65 in the left-and-right direction. The protrusion 65B provided on the front support portion 65S protrudes forward, and the protrusion 65B provided on the rear support portion 65S protrudes rearward.

A coupling member 67 is provided on the front side and the rear side of the lower guide member 65 (see FIG. 7 , FIG. 8 and FIG. 10 ). The front and rear coupling members 67 are supported by a second turning shaft 672 provided in a region below the guide part 64 in the bottom portion 40, and the front and rear coupling members 67 can be turned integrally around the second turning shaft 672. The second turning shaft 672 is provided on the left side of the protrusion 65B, that is, at a position corresponding to between the first turning shaft 661 and the protrusion 65B.

The coupling member 67 has a groove portion 67U whose longitudinal direction is along a direction away from and close to the second turning shaft 672. The width of the groove portion 67U is slightly wider than the diameter of the protrusion 65B. The protrusion 65B is inserted into the groove portion 67U and can slide along the groove portion 67U.

The first wall portion 41 or the second wall portion 42 (in this embodiment, the first wall portion 41) is provided with a driving part 68 for driving the coupling member 67 (see FIG. 7 ). The front coupling member 67 is provided with a driven gear 67N around the second turning shaft 672. The driving part 68 includes a motor 68M and a reduction gear train 68R. The reduction gear train 68R includes a worm gear 68W provided on the shaft of the motor 68M, and one or more gears 68G transferring driving force from the worm gear 68W to the driven gear 67N. When the motor 68M is driven, the driving force is transmitted to the driven gear 67N via the reduction gear train 68R, and the front and rear coupling members 67 are integrally turned.

For example, when the motor 68M is driven in the initial state shown in FIG. 8 , as shown in FIG. 10 , the coupling member 67 is turned in the counterclockwise direction around the second turning shaft 672. As the coupling member 67 is turned, the protrusion 65B slides along the groove portion 67U of the coupling member 67 in the direction away from the second turning shaft 672, so that the guide part 64 is turned in the counterclockwise direction around the first turning shaft 661 and the discharge port 69A is lifted.

On the other hand, when the motor 68M is driven in the opposite direction, the coupling member 67 is turned in the clockwise direction and the protrusion 65B slides in the direction close to the second turning shaft 672, so that the guide part 64 is turned in the clockwise direction and the discharge port 69A is lowered.

The document conveying device 120 is provided with a sensor (not shown) for measuring the amount of document G stacked on the discharge tray 43. When the amount of document G measured by the sensor is equal to or less than a predetermined amount, the controller 2 lowers the discharge port 69A to the lower limit position. The controller 2 lifts the discharge port 69A as the amount of the measured document G increases. When some or all of the documents G stacked on the discharge tray 43 are taken out, the discharge port 69A is lowered to a height corresponding to the measured amount of documents G. In other words, the controller 2 controls the discharge port lifting mechanism 34 so as to lift and lower the discharge port 69A according to the amount of documents G stacked on the discharge tray 43.

[Document Pressing Member] Next, the configuration of the document pressing member 21 will be described. FIG. 11 and FIG. 12 are perspective views showing the document pressing member 21. FIG. 13 is a front view showing the document conveying device 120 provided with the document pressing member 21.

The document pressing member 21 includes a holder part 22 provided on the lower surface of the sheet feeding tray 44 and a slide part 23 slidably held by the holder part 22 and pulled out of the holder part 22 by gravity.

The holder part 22 has a base portion 22B and a cover portion 22C. The base portion 22B is an approximately rectangular plate-shaped member having short and long sides. A shaft 24 is provided along one short side of the base portion 22B (one end portion in the longitudinal direction of the base portion 22B). The base portion 22B is arranged so that the shaft 24 is along the front-and-rear direction. The shaft 24 is supported by a support portion 44S provided on the lower surface of the sheet feeding tray 44.

The slide part 23 is an approximately rectangular plate-shaped member smaller than the base portion 22B with the same longitudinal direction as the base portion 22B. On one surface of the base portion 22B, a groove 22G having a size enough to house the slide part 23 is provided along the longitudinal direction of the base portion 22B. The groove 22G guides the sliding motion of the slide part 23 in the longitudinal direction of the base portion 22B.

The cover portion 22C is provided on the base portion 22B so as to cover the slide part 23 housed in the groove 22G. The cover portion 22C prevents the slide part 23 from deviating from the groove 22G. The groove 22G penetrates the other end side in the longitudinal direction of the base portion 22B. Therefore, the slide part 23 can be protruded and retracted from the other end side of the base portion 22B. In other words, the document pressing member 21 is extendable.

The tip end portion of the slide part 23, which is protruded from the other end side of the base portion 22B, comes into contact with the upper surface of the document G stacked on the discharge tray 43. When there is no document G on the discharge tray 43, the tip end portion of the slide part 23 comes into contacts with the upper surface of the discharge tray 43. The friction resistance between the slide part 23 and the document G is smaller than the friction resistance between the documents G. As a mechanism to reduce the friction resistance, for example, a roller (not shown) rotating around an axis along the front-and-rear direction may be provided at the tip end portion of the slide part 23. Alternatively, the tip end portion of the slide part 23 may be covered with a resin coating (not shown) such as a polyester coating.

The support portion 44S, for example, has a downward opened concave shape, houses the shaft 24 inside, and supports one or both the end portions of the shaft 24. The document pressing member 21 is turnable in the left-and-right direction around the shaft 24, but since the one end portion of the base portion 22B is surrounded by the concave support portion 44S, the turnable range of the document pressing member 21 is limited. When only gravity acts on the document pressing member 21, it is maintained with a posture slightly inclined in the counterclockwise direction to the vertical direction, as shown in FIG. 13 .

When the document G discharged from the discharge port 69A comes in contact with the document pressing member 21, the force by which the discharge roller 69 pushes the document G out is not so great as to push the document pressing member 21 away, so that the posture of the document pressing member 21 does not change, and the tip end portion of the document G is lowered along the left side surface the document pressing member 21 and penetrates between the tip end portion of the document pressing member 21 and the upper surface of the discharge tray 43. When a force greater than the force by which the discharge roller 69 pushes out the document G acts on the document pressing member 21, such as when the user removes the stacked documents G, the document pressing member 21 retreats in the counterclockwise direction without resistance so as to be prevented from being damaged.

Next, the operation of the document conveying device 120 will be described. FIG. 13 to FIG. 20 are front views showing the operation of the document conveying device 120. The document conveying device 120 includes various sensors (not shown) that detect the presence or absence of the documents G on the sheet feeding tray 44 and the discharge tray 43, the amount of the stacked documents or the like, and may be configured to control the sheet feeding tray lifting mechanism 33 and the discharge port lifting mechanism 34 according to the detection results of the sensors. However, in the following, the control contents of the sheet feeding tray lifting mechanism 33 and the discharge port lifting mechanism 34 will be limited to the basic contents, and mainly the behavior of the document pressing member 21 will be explained.

In a case where there is no document G on the discharge tray 43 when the image forming apparatus 100 and the document conveying device 120 are powered on, the controller 2 lowers the sheet feeding tray 44 and the guide part 64 to the lower limit positions (see FIG. 13 ). In this case, the amount of document G that can be placed on the sheet feeding tray 44 is the maximum. The tip end portion of the slide part 23 of the document pressing member 21 is in contact with the upper surface of the discharge tray 43 by gravity. In addition, since the slide part 23 is pushed most into the holder part 22, the length of the document pressing member 21 is minimal.

Then, when the document G is placed on the sheet feeding tray 44 and a reading start operation is performed on a display operation section (not shown), the controller 2 lifts the sheet feeding tray 44 to a height where the upper surface of the document G is in contact with the feeding roller 51 (see FIG. 14 ). At this time, since the holder part 22 lifts while leaving the slide part 23, the slide part 23 is pulled out with respect to the holder part 22, and the length of the document pressing member 21 becomes longer than when the sheet feeding tray 44 is in the lower limit position.

Then, the controller 2 controls the sheet feeding mechanism 31 and the conveying mechanism 32 to convey the document G, to make the scanner 110 read the document G and to discharge it to the discharge tray 43. When the document G is discharged, the tip end portion of the document G first comes into contact with the left surface of the document pressing member 21 (see FIG. 15 ), but the posture of the document pressing member 21 does not change and the tip end portion of the document G lowers along the left surface of the document pressing member 21. When the document G reaches the lower end portion of the slide part 23 (see FIG. 16 ), the document pressing member 21 turns slightly in the counterclockwise direction to form a gap between the slide part 23 and the discharge tray 43, and the tip end portion of the document G passes through the gap rightward (see FIG. 17 ). At this time, since the document G is pressed down by gravity acting on the document pressing member 21, the popping of the document G rightward is suppressed. In addition, because the upper surface of the discharge tray 43 is inclined so that the left side is lower, the document G slides leftward, comes into contact with the wall portion 47 and is stopped (see FIG. 18 ).

Similarly, the second and subsequent documents G are discharged and stacked on the discharge tray 43. Each time one document G is discharged, the upper surface of the documents G on the discharge tray 43 is lifted so that the slide part 23 is pushed up, but the holder part 22 is also lifted together with the sheet feeding tray 44 by the same amount so that the length of the document pressing member 21 does not change and the inclination of the document pressing member 21 does not change (see FIG. 19 ). Here, the force by which the discharge roller 69 discharges the document G has a magnitude that can overcome the frictional resistance between the documents G stacked on the discharge tray 43 and discharge the document G. On the other hand, the friction resistance between the slide part 23 and the document G is smaller than that between the documents G. Therefore, the slide part 23 does not prevent the discharge of the document G by the discharge roller 69.

When all the documents G placed on the sheet feeding tray 44 are discharged to the discharge tray 43 and then the documents G are taken out from the discharge tray 43, the height of the sheet feeding tray 44 does not change, so that the slide part 23 is pulled out from the holder part 22 by gravity and comes into contact with the upper surface of the discharge tray 43 (see FIG. 20 ). At this time, the slide part 23 is pulled out most from the holder part 22, so that the length of the document pressing member 21 is the maximum. The inclination of the document pressing member 21 does not change.

The document conveying device 120 according to the present embodiment described above includes the sheet feeding tray 44 on which the document G is placed; the discharge tray 43 provided below the sheet feeding tray 44; the conveying mechanism 32 which conveys the document G from the sheet feeding tray 44 to the discharge tray 43 via the reading position (the opening 40A); and the document pressing member 21 provided on the lower surface of the sheet feeding tray 44, capable of protruding and contracting in the directions close to and away from the discharge tray 43, and pressing the document G discharged on the discharge tray 43. With this configuration, since the posture change of the document pressing member 21 is suppressed, the variation in the effect of the document pressing member 21 pressing the document G is suppressed, and the alignment of the stacked documents G can be enhanced.

In addition, according to the document conveying device 120 according to the present embodiment, the pressing member 21 includes the holder part 22 provided on the lower surface of the sheet feeding tray 44; and the slide part 23 supported by the holder part 22 in a slidable manner and pulled out of the holder part 22 by gravity. With this configuration, the document pressing member 21 can be expandable with a simple configuration.

In addition, according to the document conveying device 120 according to the present embodiment, a frictional resistance between the document pressing member 21 and the document G is smaller than a frictional resistance between the documents G. With this configuration, the document pressing member 21 does not prevent the discharging of the document G.

In addition, according to the document conveying device 120 according to this embodiment, the sheet feeding tray lifting mechanism 33 which lifts the sheet feeding tray 44 as an amount of the document G placed on the sheet feeding tray 44 is decreased is provided. With this configuration, the document conveying device 120 can be increased in capacity.

In addition, according to the document conveying device 120 according to the present embodiment, the discharge port lifting mechanism 34 which lifts and lowers the discharge port 69A, through which the document G is discharged to the discharge tray 43, according to an amount of the document G stacked on the discharge tray 43. With this configuration, a deterioration in the alignment of the documents G on the discharge tray 43 can be suppressed.

The above embodiment may be modified as follows.

In addition to the above configuration, the holder part 22 may be provided with a biasing means (not shown), such as a spring, for biasing the slide part 23 toward the discharge tray 43. With this configuration, the certainty of contact of the slide part 23 with the document G can be enhanced.

In addition to the configuration of the above embodiment, an actuator (not shown) may be provided to change the amount of protrusion of the slide part 23 from the holder part 22 according to the distance between the lower surface of the sheet feeding tray 44 and the upper surface of the documents G stacked on the discharge tray 43. With this configuration, the length of the document pressing member 21 can be optimized according to the distance between the lower surface of the sheet feeding tray 44 and the upper surface of the documents G stacked on the discharge tray 43. The distance between the lower surface of the sheet feeding tray 44 and the upper surface of the documents G stacked on the discharge tray 43 may be calculated from the measurement results of a sensor (not shown) measuring the height of the sheet feeding tray 44 and a sensor (not shown) measuring the height of the upper surface of the documents G stacked on the discharge tray 43, or may be measured directly by a sensor (not shown) provided on the lower surface of the sheet feeding tray 44.

The document pressing member 21 according to the above embodiment has a double structure with the holder part 22 and the slide part 23, but may have a triple structure with a second slide part (not shown) slidably supported by the slide part 23 and pulled out of the slide part 23 by gravity. With this configuration, the ratio of the minimum length to the maximum length of the document pressing member 21 can be increased as compared with the case of the double structure, and the larger capacity of the document conveying device 120 can be accommodated. In addition, the ratio between the minimum length and the maximum length can be further increased by forming the document presser member 21 into four or more multiple structures.

In addition to the configuration of the above embodiment, the support portion 44S may be provided with a biasing means (not shown), such as a spring, for biasing the document pressing member 21 in the clockwise direction around the shaft 24. With this configuration, the certainty of contact of the slide part 23 with the document G can be enhanced.

The document pressing member 21 according to the above embodiment may be provided in the document conveying device 120 without the sheet feeding tray lifting mechanism 33. Also, the document pressing member 21 according to the above embodiment may be provided in the document conveying device 120 without the discharge port lifting mechanism 34. 

1. A document conveying device comprising: a sheet feeding tray on which a document is placed; a discharge tray provided below the sheet feeding tray; a conveying mechanism which conveys the document from the sheet feeding tray to the discharge tray via a reading position; and a document pressing member provided on a lower surface of the sheet feeding tray, capable of protruding and contracting in directions close to and away from the discharge tray, and pressing the document discharged on the discharge tray.
 2. The document conveying device according to claim 1, wherein the pressing member includes: a holder part provided on the lower surface of the sheet feeding tray; and a slide part supported by the holder part in a slidable manner and pulled out of the holder part by gravity.
 3. The document conveying device according to claim 1, wherein a frictional resistance between the document pressing member and the document is smaller than a frictional resistance between the documents.
 4. The document conveying device according to claim 1, further comprising: a sheet feeding tray lifting mechanism which lifts the sheet feeding tray as an amount of the document placed on the sheet feeding tray is decreased.
 5. The document conveying device according to claim 1, further comprising: a discharge port lifting mechanism which lifts and lowers a discharge port, through which the document is discharged to the discharge tray, according to an amount of the document stacked on the discharge tray.
 6. The document conveying device according to claim 1, wherein a tip end of the document pressing member comes into contact with the discharge tray or the document.
 7. The document conveying device according to claim 1, wherein the document pressing member is turnable around a shaft provided in the discharge tray within a predetermined range in a discharge direction of the document and in an opposite direction to the discharge direction.
 8. The document conveying device according to claim 7, wherein the document pressing member is inclined to the shaft in the discharge direction. 